Insert rods

F

Flat32

Member
Please excuse my ignorance here where my only excuse is being new to Model A/B engines. Mine is a B and when one of the rod babbits gave out I did a little research and rashly determined all I needed to do was buy a set of inserted rods and then not have to worry about babbit failure. Spent $700 for a set of Snyder's new B rods with .010 over inserts thinking they would be fine with my crank which measured 1.8645 +or- .0001 with no out of round or tapered condition.

Rods are beautiful in all respects although side clearance is on the tight side at .007. Did a plastigage check which seemed to indicate .001 clearance which, to me seemed a bit tight for a dipper lubricated bearing.

Well, the first one I installed with assembly lube on the journal locked up tight when torqued. Installed the other three and same thing.

My only option is to shim the rod caps, but the only shims I find are the laminated ones designed for babbit rods. To shim my inserted rods I need steel shims that will extend over the insert edges to maintain crush.

Is such an animal available or do I have to bite the bullet and make them??

I've read through the recent Snyder's inserted rods posts and I'm guessing the inserts are designed to have the clearance on the crank and babbit typically has the clearance. I should have checked before I set the crank, however grinding .001 off of already ground journals to me would be troublesome and polishing that much accurately isn't terrible easy either which would have lead me back to shimming.

My thinking is .002 shim on each side of the cap.

Ray
 
The diameter will still be small at the parting line if you shim the cap ---

Have you measured the bore of the rods to see if they are undersized or out of round?

Perhaps the inserts can be bored ---there is an old sunnen attachment that was meant for finishing inserts ---and there are rod boring machines
 
Rod bores are round. Insert inside diameters measure round when installed in the rods. Inserts have .002 of crush measured with feeler with rod bolts just snug. Assembled to crank dry with prussian blue applied very thinly to the crank transfers to the entire insert surface. Seems to have a couple tenths interference fit.

Looks like I'm going to bite the big bullet and bore out the inserts to make it a correct fix. Piece of cake, right??:rolleyes:

Ray
 
Flat32 said:
Rod bores are round. Insert inside diameters measure round when installed in the rods. Inserts have .002 of crush measured with feeler with rod bolts just snug. Assembled to crank dry with prussian blue applied very thinly to the crank transfers to the entire insert surface. Seems to have a couple tenths interference fit.

Looks like I'm going to bite the big bullet and bore out the inserts to make it a correct fix. Piece of cake, right??:rolleyes:

Ray
Click to expand...


OOooooo Ray, ....I ain't sure you are walking into the right alley! Why not take the crank and the rods over to a good machine shop and have them mic both and see exactly where you are. Then depending on how far, either have them polish or grind the crank to the correct size. Boring the inserts not only cuts down on the useful life of the bearing, but the same procedure would need to be done in the future should a bearing need to be replaced. My advice, bite the bullet and machine the crank. In my area this runs about $100.00. Just make sure the grinder knows how to properly do the set-up to find the center.
 
Brent is correct. Better to mess up a 100 dollar crank than to destroy 700 dollars of rods. Mind you, the rods could always be brought back to their original bore but that is also kind of costly and takes a good automotive machinist to get the job correct. I would say also, if you open the inside of the rod up you will make it too big for the insert and destroy the geometry of the assembly. This would be a recipe for disaster and a spun rod bearing. The inserts are designed for a rod with a specific bore and the tolerance is usually .0005. Do the crank, it is more work but a better option in the long run.
 
Did you call Snyders and get their opinion? I would try going to the machine shop with the assemble rod and measure the bore. Then measure the bearing shell thickness. There is a mic for this. you could probably improvise with a small ball bearing on the inside of the shell if you cannot find one. After you have all your numbers call Snyders if it appears to be a problem with the product. It may be possible to hone the rod itself to give the bearing clearance. For whatever reason this may be the problem. Brent and James are correct but it would nag me that something that should fit out of the box did not. I would have to find out why.
 
There is only one way to do it. The right way is fix the crank if you go boring out inserts you might destroy them. Most inserts do not have that much extra bearing material on them.
Did you call synders and find out what size your crank should be for those bearings. Are you measuring with micks are they set right.
 
I'm a little confused. Is the crank journal measurement he gave oversized? I am not familiar with what it should be off the top of my head. It is my understanding you would not hone the bearing shell but instead the rod before the shell is inserted. He mentions crush on the shell at .002. Should that even be happening?
 
Frank Miller said:
I'm a little confused. Is the crank journal measurement he gave oversized? I am not familiar with what it should be off the top of my head. It is my understanding you would not hone the bearing shell but instead the rod before the shell is inserted. He mentions crush on the shell at .002. Should that even be happening?
Click to expand...

Bearing crush is very important you do not want to mess with that. Bore the rod to big the insert will spin. To small it will distort to much.
I think he is about .001 to big on the crank shaft dia. But I'm not sure what size it should be for those bearings. .001 is about 1/3 the thickness of a average human hair.
There is only one way to do bearings and that is get every thing right. Other wise you are going to do it again or some one else will.
 
Flat32,​

Don't shim the rods. As others have previously stated, shimming them will change the geometry of the bearing and mess with the required bearing shell "crush".​

The "B" insert rods you purchased from Snyder's were manufactured by Antique Engine Rebuilding (AER). You should find the marking AER on the rod. The insert bearing you received with the rods should be aluminum bearing surface applied over steel shells. (Rich from AER, switched from babbitt to aluminum a while back.)​

The following was lifted from Snyder's online site:​



New forged connecting rods with insert bearings. These rods are made to accept the original style wrist pins. Sold in sets of 4 with bearings. 1932-34. U.S.A.

Possible solution:
If the inserts are aluminum lined, they may be able to be honed to fit your journal. I spoke to Rich a few weeks ago regarding adjusting the final fit of these same "B" rods. His comment: "Just touch the bearing surfaces of the inserts with a hone to open them up a bit." The shell would be clamped in the rod under 35# torque to complete the process. Call Rich at AER to discuss the actual procedure before attempting it. Let him know your journal sizes and verfiy the desired clearance with him. He will let you know if you can remove the amount of material required to fit your crankshaft. Using the general guideline of .001" of clearance per 1" of journal size, the minimum desired clearance should be about .002". From your measurements, you do not need to remove much from the rod inserts.​

Rich's phone number: (847) 674-6716 Call him...he is a wealth of knowledge and always willing to share it!​


The journal specs for AER "B" connecting rods are:​

CRANKSHAFT ROD JOURNAL SIZE STANDARD 1.8730/1.8740
CRANKSHAFT ROD JOURNAL SIZE .010 UNDERSIZE 1.8630/1.8640
CRANKSHAFT ROD JOURNAL SIZE .020 UNDERSIZE 1.8530/1.8540
CRANKSHAFT ROD JOURNAL SIZE .030 UNDERSIZE 1.8430/1.8440
CRANKSHAFT ROD JOURNAL SIZE .040 UNDERSIZE 1.8330/1.8340
CRANKSHAFT ROD JOURNAL SIZE .060 UNDERSIZE 1.8130/1.8140​

FYI: I also had a tight fit on a "B" project a few weeks ago and after speaking with Rich, I lightly honed the "B" insert using a fine stone and lots of oil. It opened the clearance to where I wanted it and all is fine. I cleaned the inserts multiple times after honing. I would not have tried honing the early babbitt inserts as I would have been concerned about residual stone grit in the babbitt.​

Good luck with your project.
Dave in MN
www.durableperformance.net​
 
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Dave in MN said:
Flat32,​

Don't shim the rods. As others have previously stated, shimming them will change the geometry of the bearing and mess with the required bearing shell "crush".​

The "B" insert rods you purchased from Snyder's were manufactured by Antique Engine Rebuilding (AER). You should find the marking AER on the rod. The insert bearing you received with the rods should be aluminum bearing surface applied over steel shells. (Rich from AER, switched from babbitt to aluminum a while back.)​

The following was lifted from Snyder's online site:​



New forged connecting rods with insert bearings. These rods are made to accept the original style wrist pins. Sold in sets of 4 with bearings. 1932-34. U.S.A.

Possible solution:
If the inserts are aluminum lined, they may be able to be honed to fit your journal. I spoke to Rich a few weeks ago regarding adjusting the final fit of these same "B" rods. His comment: "Just touch the bearing surfaces of the inserts with a hone to open them up a bit." The shell would be clamped in the rod under 35# torque to complete the process. Call Rich at AER to discuss the actual procedure before attempting it. Let him know your journal sizes and verfiy the desired clearance with him. He will let you know if you can remove the amount of material required to fit your crankshaft. Using the general guideline of .001" of clearance per 1" of journal size, the minimum desired clearance should be about .002". From your measurements, you do not need to remove much from the rod inserts.​

Rich's phone number: (847) 674-6716 Call him...he is a wealth of knowledge and always willing to share it!​


The journal specs for AER "B" connecting rods are:​

CRANKSHAFT ROD JOURNAL SIZE STANDARD 1.8730/1.8740
CRANKSHAFT ROD JOURNAL SIZE .010 UNDERSIZE 1.8630/1.8640
CRANKSHAFT ROD JOURNAL SIZE .020 UNDERSIZE 1.8530/1.8540
CRANKSHAFT ROD JOURNAL SIZE .030 UNDERSIZE 1.8430/1.8440
CRANKSHAFT ROD JOURNAL SIZE .040 UNDERSIZE 1.8330/1.8340
CRANKSHAFT ROD JOURNAL SIZE .060 UNDERSIZE 1.8130/1.8140​

FYI: I also had a tight fit on a "B" project a few weeks ago and after speaking with Rich, I lightly honed the "B" insert using a fine stone and lots of oil. It opened the clearance to where I wanted it and all is fine. I cleaned the inserts multiple times after honing. I would not have tried honing the early babbitt inserts as I would have been concerned about residual stone grit in the babbitt.​

Good luck with your project.
Dave in MN
www.durableperformance.net​
Click to expand...

Good answer he should know.
George
 
I agree, call Rich and discuss it with him. He makes them and uses them all the time. He knows what works. Then, please let us know what he says.
 
inserts can be shimmed, just be sure that the shim covers the cap and the insert, this will maintain the proper crush which is what holds the insert in place. The tang just locates it. I would not put in more than .001" or .002" thickness of shims though. Steel shims would be better than brass.
 
Dave in MN has provided the most definitive and comprehensive answer I could have hoped for and on very short notice.

For what it's worth I was a tool and die maker in a past life and I have the measuring tools and I have a small CNC machine that can bore the inserts. Moderately challenging, but doable.

I don't have a crank grinder or a hone or any personal experience with the local shops that do so no established faith in their abilities and no relationships where I'd be guaranteed the work was being done by the most skilled worker on site.

Sure would have been nice if the specific crank journal size info was provided by Snyder or AER with the rods, but then again I could have asked instead of assuming. No harm done.

Also have to mention I find it heartening that this site has such a high regard for correctness and respect for precision where it counts coupled with what seems to be a dedicated willingness to share.

Ray
 
I would polish half a thou off the crank before I messed with the inserts. Face it, you never did anything to the crank and your measurements show it big by half to one thou. BTW, you will find the crank always grinds different for inserts than it does for babbitt. I keep them separate on my shelf clearly marked.
 
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Just to let you guys know I bored the inserts today and they are installed. Took the better part of the day being cautious and methodical beyond my normal habits, but the process went without a hitch and I've got between .0017 and .0020 clearance on all four.

At top center where ring drag is the least I can turn the crank by hand with the front pulley.:cool:

Thanks

Ray
 
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